My examples will be minor metro areas, but they will serve your point and help with your question--which I thank you for.

I remember when there was only one home in what is now called Vail, CO. It belonged to a Dartmouth man who had, in his words, a bad war (WWII) and come west with his bride to raise a family in wild country. He ran a mill that produced timbers for the mines in Minturn. That would have been 1959-60. As a college kid I helped build either the fifth or seventh house in Vail; there was no place to rent so I slept in a Whelen lean-to under oh so brilliant stars.That would have been 1964. Now Vail has a population of over 5,000 and stretches for miles down the valley.

I remember when you could not drive down a VW down the main street in Telluride, CO because of the potholes. I remember when Park City was a ghost town with no gas station after sundown. Now it has 8,000 peopIe. I remember when you could drive through Hanksville or Boulder, UT and not know you were driving through a town--no lights. None.

When I came to live in the Tetons in 1978 after returning from Asia I lived under black zone skies for several decades Then they turn grey. Now many areas are green and blue. Still, three decades under black and grey skies is not bad. But I miss them and mourn them.

In the technical literature there is mention of "generational amnesia" and "sliding benchmarks:" the fact that old standards are forgotten by each generation as they come to accept a diminished land or sky or run of salmon or insect populations as "normal." We used to have blizzards of salmon flies in June. They are gone now. If you don't know what you have lost, how can you pine for it? I pine a lot these days, especially for Wyoming and Utah.

I believe these maps and memories and ruminations are necessary to fight creeping LP. Sort of like the Quakers bearing witness.

I'd love to see the growth in some of the major metro areas of the U.S. That would show another way of looking at the impact of growth on local light pollution.

Yes, and data on population is much easier to obtain than data on skyglow. Obviously, they track together pretty well.

The answers will vary hugely regionally. There's been substantial growth in the South and even more in the Southwest, but relatively little change here in the Northeast over the last 30 years or so.

One thing Census Bureau figures might not reflect is the growth of second homes. An individual home has no measurable impact in a city or suburb, but it can have a major effect if it's an inholding surrounded by wilderness.

I would also note that restricting the problem to urban growth and the lighting it entails may ignore the main problem. Wyoming's population has increased by approximately 100,000 over the past 25 years (to around 575,000), but the increase in light pollution has not been mainly in urban areas--to the degree that Wyoming even has urban areas--but in formerly remote areas developed for gas and oil production, plus an increase in coal mining, all of which generate lots of light pollution. I'm all for better lighting, everywhere; however, it's only the tip of the iceberg.

And this exponential growth of urban sprawl is precisely why light pollution regulations and measures can never hope to more than somewhat slow spreading light pollution. For anyone who has been in the hobby for a really long time, their observation of worsening conditions illustrate that the loss of dark skies overall, as well as the distance at which light sources can significantly impact the sky brightness, is far beyond any hope of real control. The only exception to this being perhaps in those areas undesirable for human habitation and industry.

And this exponential growth of urban sprawl is precisely why light pollution regulations and measures can never hope to more than somewhat slow spreading light pollution. For anyone who has been in the hobby for a really long time, their observation of worsening conditions illustrate that the loss of dark skies overall, as well as the distance at which light sources can significantly impact the sky brightness, is far beyond any hope of real control. The only exception to this being perhaps in those areas undesirable for human habitation and industry.

Actually, the global trend since 1997 is flat - about 77,000,000 a year increase. Going back 10 years further, population growth has declined from the 1987 high of around 87 million. So the growth is no longer exponential, it is currently (over the past 15 years) linear; almost a constant. Forecasts are for a long slow decline in global population growth in absolute terms for the next several decades.

However, if the standard of living continues to increase in many less-developed countries, the amount of light produced per capita will increase due to the abiity to afford it.

The same is approximately true for US growth. Growth over the past decade is approximately a constant, running between 2.5-2.8 million people per year. Since the earliest of us baby boomers are now in their late 60's, the growth over the next couple decades will be further moderated by our demise.

In the US, the trend is clearly towards more efficient lighting, using less energy, and to an increasing extent, using full (or partial) cutoff fixtures. The overall light pollution here won't decrease until substantial retrofits are made, replacing existing fixtures in large amounts. But two decades from now, it will likely be no brighter at night than it is today; and quite possibly darker.

The technology for the near future seems to be LEDs, which are fundamentally monochromatic. If we could get a national standard for outdoor lighting that set the wavelengths to just a few - say mostly green at 540-560 for efficient vision and some red around 630 for color, then I'm quite confident our hobby's suppliers could provide us with great filters, just as they can for low pressure sodium, for example.

Hermit, your outlook on the future is, in my opinion; far rosier than what is self evident where ever I travel in the U.S.

Although sprawl has reduced temporarily because of the sharp economic down-turn of a few years back, it is already beginning to resume in most areas. Concurrently, while legal population figures indicate a modest linear growth in population, there is a very significant increase in all quarters of the country in those not being counted and their numbers will potentially increase dramatically dependent of coming legislation.

At the same time fewer and fewer established young couples wish to reside in the inner suburbs and flee ever further outside them. They bring with them the desire for street illumination, a fear of the dark and further local commercial development to serve their needs. I have a fine example of a young ex-urban couple down the street from me who moved in and installed 17...YES SEVENTEEN... unshielded flood lights around the outside of their house "for security"! This is hardly an isolated instance in my developing area. Most homes have multiple totally unshielded light...and the residents insist that is the kind of full yard illumination they desire to have!

As to replacing current outdoor lighting with new limited spectrum lighting units that observers will be able to filter out, this same fiction was promoted back in the day in regard to first Mercury vapor, then low pressure Sodium and then high pressure Sodium lighting. Each stage touted to be better overall for observers turned out to be orders of magnitude worse than the last, until the skies turned orange at night. Currently I reside 75 miles due north of NYC and my skies are as bad as they were back in 1965 when I lived on the very border with NYC itself and each year it is getting worse.

It's nice to dream about some future observers' Utopia like that espoused by the Dark Sky Society and others, but the reality is that the best skies for the vast majority of the U.S. population are probably already long in the past.

Hermit, your outlook on the future is, in my opinion; far rosier than what is self evident where ever I travel in the U.S.

I'm somewhere in between you. I agree that light pollution is likely to increase overall, but I don't think the fight is hopeless.

There are really three separate issues here: population growth, dispersal, and lighting standards.

Population growth will surely increase in the U.S. for a long time to come, though presumably at its current, fairly measured rate.

I think that dispersal -- or suburban sprawl if you prefer -- is episodic rather than linear. There was obviously a huge burst in the 50s and early 60s and another huge burst from the 80s to the recent crash. My gut feeling is that we won't see another burst for quite some time, for several reasons. First, the recent boom carried to huge excess, so that there's now a big overhang of unsold property. Second, recentralization has become fashionable; inner cities have increased in population for the first time in generations, and this trend is extending to inner suburbs as well. Finally, suburban sprawl presupposes cheap energy (for home heating as well as transportation), and energy prices are likely to rise for some time to come.

The fact that urban population is increasing is particularly encouraging, because light pollution per capita is much smaller in dense cities than in suburbs. And it is more or less capped; no matter how many more people move in, you don't need any more streetlights.

On the other hand, telecommuting is likely to encourage dispersion. It seems to me that telecommuting has barely begun to tap its potential; many jobs that are traditionally centralized can be done as well or better without requiring people to show up in the office every day.

I think that BrooksObs has a somewhat jaundiced point of view on this subject because he lives in an area that was largely rural a generation ago and is now increasingly suburban. He was a pioneering exurbanite, and the masses have caught up with him. It's a qualitative rather than quantitative change. But 30 miles closer to New York City -- where it was suburb a generation ago -- or 30 miles farther away, light pollution has changed very little in the last three decades.

As for the nature of the lighting that we use -- that's up to us! LEDs have great promise and great menace. Which it will be is a matter of choice, not destiny.

"I think that BrooksObs has a somewhat jaundiced point of view on this subject because he lives in an area that was largely rural a generation ago and is now increasingly suburban. He was a pioneering exurbanite, and the masses have caught up with him. It's a qualitative rather than quantitative change. But 30 miles closer to New York City -- where it was suburb a generation ago -- or 30 miles farther away, light pollution has changed very little in the last three decades." - Tony

Tony, if you think that light pollution hasn't changed much everywhere in this country over the past three decades, I know for a fact that you are very much mistaken.

In my travels across the country I've seen locations steadily become drowned in excessive outdoor lighting. Flying over the continent at night is more depressing each time. The U.S. has reached a point where every little farm yard even has outdoor floodlighting. One can see clear evidence of the great metropolis of the NYC area at up to 150 miles out of the city today. In New England, save for the extreme north just a little short of the border, vitually all locations today are impacted to some degree by light pollution. I even seen it from the Texas Star Party site. I've witnessed all of these have grow very steadily worse over the last 30 years.

I think that much of this isn't actually recognized by hobbyists such as yourself because of the magnitude of the damage already present when you first entered the hobby. I'm often told of sites considered absolutely great by observers in say their 30's and 40's. But on visiting the sites myself they are found to be no more than mediocre due to sky brightness. I really believe that most observers today no longer actually know what a truly unpolluted sky looks like as a base for comparison and this I honestly find quite shocking. And lacking that baseline one cannot recognize the degree of subsequent progressive loss nearly so easily.

So, my views on the evolving situation are by no means jaundiced. Rather, the would be better classified as the observations of someone with a much broader working knowledge of the situation than is possessed by most.

Tony, if you think that light pollution hasn't changed much everywhere in this country over the past three decades, I know for a fact that you are very much mistaken.

No, I didn't say that. Parts of the United States have experienced explosive growth and sprawl in the last three decades, most notably Texas, Arizona, and Nevada. However, the Northeast isn't one of those areas. Most of the growth here has been in the outer suburbs, and even there it has been fairly modest.

I have irrefutable, objective measurements proving that light pollution has been essentially unchanged over the last 8 years at all of my customary observing sites, which range from city to inner suburb to outer suburb to rural.

These measurements substantiate my observation that conditions have not changed perceptibly at these sites over the 16 years that I have been recording sky conditions subjectively but carefully. And although my interest in astronomy was casual 30 or 40 years ago, I don't think that light pollution at the sites that I did use then has changed much over that time frame, either.

The U.S. has reached a point where every little farm yard even has outdoor floodlighting.

Yes, Leslie Peltier commented on that in 1965 in his book Starlight Nights. It is not a new phenomenon.

One can see clear evidence of the great metropolis of the NYC area at up to 150 miles out of the city today. In New England, save for the extreme north just a little short of the border, vitually all locations today are impacted to some degree by light pollution.

I agree with both of those statements. But I think they were true in 1983 as well.

Tony, do you read your own posts? Upstream you wrote: "It's a qualitative rather than quantitative change. But 30 miles closer to New York City -- where it was suburb a generation ago -- or 30 miles farther away, light pollution has changed very little in the last three decades." Then in a subsequent post you turn around and admit that the NYC lightdome is visible 150 miles outside NYC today, a situation that was absolutely unimaginable 25 years ago. Ask posters from the outermost suburbs of Chicago, Washington, LA, and Houston if they haven't seen a marked increase in light in recent decades. Today amateur astronomers live mostly somewhere near cities, so perhaps 80%-90% are impacted and report declining conditions if asked.

In fact, the light pollution situation has altered drastically over that same period, not only in NY/New England but just about everywhere I've traveled. Your status as a casual observer is hardly critical enough to establish any sort of baseline for a critical comparison. At the same time, in my experience so-called dark sky meters do not necessarily reflect what the observer's eye perceives. I've seen some absurd claims made for sky measurements taken at sites (like Stellafane) in New England that supposedly rival those obtained at remote professional observatories. Having visited both, the story told by sky meter readings becomes questionable, at best.

I appreciate that your job at Sky hinges on promoting the hobby and acknowledgement that the situation is not good and obviously worsening steadily (not just intermittently) with the years is bad for business. Still, it is sad to see newer hobbyists being misled into thinking that even those with honestly marginally good skies today won't likely see a marked deterioration as time passes, or that innovations in outdoor lighting will lead to a return of darker skies in the future.

Your status as a casual observer is hardly critical enough to establish any sort of baseline for a critical comparison.

Agreed. My observations going back 16 years are not casual at all, so I put a lot of credence in them, though they're no substitute for instrumental measurements. But back before 16 years, they have to be classed as anecdotal.

I do have some star-trail photos that I did 40 years ago, and I have some hope of retrieving useful data from them. But I haven't figured out how yet.

At the same time, in my experience so-called dark sky meters do not necessarily reflect what the observer's eye perceives. I've seen some absurd claims made for sky measurements taken at sites (like Stellafane) in New England that supposedly rival those obtained at remote professional observatories. Having visited both, the story told by sky meter readings becomes questionable, at best.

Sorry, you are on very weak ground here. The Sky Quality Meter does have its limitations, which I could describe in great detail. It is also fairly easy to use them wrong and obtain wildly inaccurate results. But in the hands of an experienced user they are extremely accurate scientific instruments -- far more accurate and repeatable than any subjective judgment.

I appreciate that your job at Sky hinges on promoting the hobby and acknowledgement that the situation is not good and obviously worsening steadily ...

It's why we now recommend a 10" dob. 10 years ago, it was an 8" dob, and 10 years before that, a 6" dob. There was a time a 6" Dob/Newt was considered a real high-end scope and a 4" Refractor was considered huge......

6" and 8" Newtonians were common amateur instruments in the 1960s and 1970s. I would still recommend an 8" f/6 (or f/7) as a first telescope, and a lifelong acquisition. Whatever else you own, it will still have its uses.

I think sizes have gone up in general in the last 20 years because Dobsonian mounts are cheaper, and the flood of Chinese telescopes are cheaper, so people can move up in aperture.

BrooksObs, I'm neither an optimist nor a pessimist about population growth. I simply stated the facts presented by the US Census, over a number of decades of historical data. You are welcome to ignore or dispute the facts; it makes no difference to either me or to them.

Where I live, upstate NY, population has been declining since the 1970's. I live in Broome Co, and both it, and all the surrounding NY & PA counties have had population declines. My second home in the Adirondacks also has little to no population increase and the Nature Conservancy just purchased about a third of the land in the central Adirondacks to donate to the state forest preserve.

On the flip side: PA has frack'ing and southern NY may soon have it too. There is also a trend for 'industrial sprawl': new 'tech' industry does not want the old down-town factory buildings, and build new facilities on 'green' land - supposedly because of better highway access. Anti-LP law could help with this, but alas, it has never passed in NY.

BTW, a few of those on-line SQM readings for Stellafane seem bogus to me. However, the sky brightness varies a great deal there for the same reason it does around my southern NY home: 80+ percent of the people live in a river valley that sometimes fogs up (holding in the light) while it is clear on the high grounds. The difference is very noticeable. Humidity also impacts sky brightness. My own SQM readings at Stellafane over the years have varied from 20.9 to 21.5 (mostly 21.2), and visually the appearance had the same difference. There is a light dome to the north at all times.

I'll expand on the Stellafane experience a step further from the visual standpoint. When I first started attending the conventions back in the early 1960's the place was as dark as can possibly be imagined, fully equal to many of the observatory sites in the American SW that I visited subsequently. No trace whatever of the village of Springfield, or surrounding villages, could be detected from the mountain, only the aircraft warning lights on hills far to the north.

With the passage of the years I saw the light-dome form over the village, at first hardly visible. But it brightened and rose as time passed. By the mid 1980's it reached half way up the eastern sky and at least weakly attained the zenith around 2000. By that time Brattleboro far to the south was clearly apparent from the new campgrounds. Today, unless the village is shrouded in ground fog, its light dome diffuses somewhere into the western sky and there is minor interference all around.

Don't get me wrong, Stellafane's skies are still superior to pretty much what any of the rest of us endure from home, but it still is a marked and obvious decline relative to what once was. Incidentally, beginning about 1995-2000, when driving home on some Saturday nights, I note that no actually dark sky location exists anywhere south of Stellafane along Rt 91 any more all the way to the coast. A rather sad commentary on our plight indeed.

By that time Brattleboro far to the south was clearly apparent from the new campgrounds.

It's hard to trace a light dome to any single source; after all, there are towns along the Connecticut all the way from its source to Long Island Sound. And headlights on I-91 generate a huge amount of light, too. My guess is that Brattleboro is a fairly minor contributor. Locals say that the compact bright source to the south is actually a truck stop on I-91.

My house in CT was in a yellowish zone in 1998-now it is a solid orange with red not far to the west. My first real awareness of light pollution per se and its' impacts upon astronomy was in 1986 where I had to go to the outskirts of Port Orange Florida to gain a glimpse of Halleys Comet. Even there it was a sketchy. That "remotish" road locations where I escaped some of the lp, of course, has expanded to a massive through way and is nested in miles of sprawl. All this happened in a single decade-Florida's destruction is one of the great ecological tragedies of the lower 48 as well as an astronomical tragedy. Some of the darkest and steadiest skies in the nation are now bathed in car dealership lights and strip mall lighting-some of which is directed up so you will know where to shop in the day......